Conductive Geopolymers as Low-Cost Electrode Materials for Microbial Fuel Cells

Abstract

Geopolymer (GP) inorganic binders have a superior acid resistance compared to conventional cement (e.g., Portland cement, PC) binders, have better microbial compatibility, and are suitable for introducing electrically conductive additives to improve electron and ion transfer properties. In this study, GP–graphite (GPG) composites and PC–graphite (PCG) composites with a graphite content of 1–10 vol % were prepared and characterized. The electrical conductivity percolation threshold of the GPG and PCG composites was around 7 and 8 vol %, respectively. GPG and PCG composites with a graphite content of 8 to 10 vol % were selected as anode electrodes for the electrochemical analysis in two-chamber polarized microbial fuel cells (MFCs). Graphite electrodes were used as the positive control reference material. Geobacter sulfurreducens was used as a biofilm-forming and electroactive model organism for MFC experiments. Compared to the conventional graphite anodes, the anode-respiring biofilms resulted in equal current production on GPG composite anodes, whereas the PCG composites showed a very poor performance. The largest mean value of the measured current densities of a GPG composite used as anodes in MFCs was 380.4 μA cm–2 with a standard deviation of 129.5 μA cm–2. Overall, the best results were obtained with electrodes having a relatively low Ohmic resistance, that is, GPG composites and graphite. The very first approach employing sustainable GPs as a low-cost electrode binder material in an MFC showed promising results with the potential to greatly reduce the production costs of MFCs, which would also increase the feasibility of MFC large-scale applications.

Microbial Electrochemical Systems and Membrane Bioreactor Technology for Wastewater Treatment

“…Glass fiber mats of different thicknesses were tested in MFCs together with J‐cloth and CEM. In comparison, the 1.0 mm thick glass fiber mats and J‐cloth showed similar maximum power densities (790 mW m −2 ) and performed significantly better than the CEM 84. The Coulombic efficiency (CE) of MFCs with 1.0 mm thick non‐biodegradable glass fiber mats (81 %) is significantly higher than that of J‐cloth.…”

“…Metal as anode electrode is used due to its conductivity and electron flow [84]. Metals have low interfacial impedance and low internal resistance compared to carbon-based materials [85].…”

Geopolymer Based Electrodes as New Class of Material for Electrochemical CO2 Reduction

“…In a previous study, we demonstrated that the addition of graphite to GP‐mortar can lead to electrically conductive GP‐electrodes [26] . It was assumed that a graphite network was formed inside the GP, which allowed the application of the modified GP as electrode.…”

Theoretical Studies of Adsorption Reactions of Aluminosilicate Aqueous Species on Graphene-Based Nanomaterials: Implications for Geopolymer Binders

“…Geopolymers have attracted the attention of researchers recently and have demonstrated much better compatibility with carbon-based (nano)­materials in preparing functional cementitious composites than Portland cement . Depending on the kind of raw material selection and processing conditions, geopolymer binders exhibit an extensive variety of properties and characteristics, including low shrinkage, high compressive strength, fast or slow setting, fire resistance, increased acid resistance in comparison to Portland cement, and low thermal conductivity. , Most of the CNT-geopolymer research has focused on physically dispersing CNT into alkaline activators through ultrasonication and/or the use of surfactants and superplasticizers.…”